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Diffstat (limited to '')
-rw-r--r-- | include/comphelper/threadpool.hxx | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/include/comphelper/threadpool.hxx b/include/comphelper/threadpool.hxx new file mode 100644 index 0000000000..84f9dc9284 --- /dev/null +++ b/include/comphelper/threadpool.hxx @@ -0,0 +1,114 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + */ + +#ifndef INCLUDED_COMPHELPER_THREADPOOL_HXX +#define INCLUDED_COMPHELPER_THREADPOOL_HXX + +#include <sal/config.h> +#include <rtl/ref.hxx> +#include <comphelper/comphelperdllapi.h> +#include <mutex> +#include <condition_variable> +#include <cstddef> +#include <vector> +#include <memory> + +namespace comphelper +{ +class ThreadTaskTag; + +class COMPHELPER_DLLPUBLIC ThreadTask +{ +friend class ThreadPool; +friend struct std::default_delete<ThreadTask>; + std::shared_ptr<ThreadTaskTag> mpTag; + + /// execute this task + void exec(); +protected: + /// override to get your task performed by the pool + virtual void doWork() = 0; + /// once pushed ThreadTasks are destroyed by the pool + virtual ~ThreadTask() {} +public: + ThreadTask(std::shared_ptr<ThreadTaskTag> pTag); +}; + +/// A very basic thread-safe thread pool implementation +class COMPHELPER_DLLPUBLIC ThreadPool final +{ +public: + /// returns a pointer to a shared pool with optimal thread + /// count for the CPU + static ThreadPool& getSharedOptimalPool(); + + static std::shared_ptr<ThreadTaskTag> createThreadTaskTag(); + + static bool isTaskTagDone(const std::shared_ptr<ThreadTaskTag>&); + + /// returns a configurable max-concurrency + /// limit to avoid spawning an unnecessarily + /// large number of threads on high-core boxes. + /// MAX_CONCURRENCY env. var. controls the cap. + static std::size_t getPreferredConcurrency(); + + ThreadPool( std::size_t nWorkers ); + ~ThreadPool(); + + /// push a new task onto the work queue + void pushTask( std::unique_ptr<ThreadTask> pTask); + + /** Wait until all queued tasks associated with the tag are completed + @param bJoin - if set call joinThreadsIfIdle() at the end + */ + void waitUntilDone(const std::shared_ptr<ThreadTaskTag>&, bool bJoin = true); + + /// join all threads if there are no tasks presently. + void joinThreadsIfIdle(); + + /// return true if there are no queued or worked-on tasks + bool isIdle() const { return maTasks.empty() && mnBusyWorkers == 0; }; + + /// return the number of live worker threads + sal_Int32 getWorkerCount() const { return mnMaxWorkers; } + + /// wait until all work is completed, then join all threads + void shutdown(); + +private: + ThreadPool(const ThreadPool&) = delete; + ThreadPool& operator=(const ThreadPool&) = delete; + + class ThreadWorker; + friend class ThreadWorker; + + /** Pop a work task + @param bWait - if set wait until task present or termination + @return a new task to perform, or NULL if list empty or terminated + */ + std::unique_ptr<ThreadTask> popWorkLocked( std::unique_lock< std::mutex > & rGuard, bool bWait ); + void shutdownLocked(std::unique_lock<std::mutex>&); + void incBusyWorker(); + void decBusyWorker(); + + /// signalled when all in-progress tasks are complete + std::mutex maMutex; + std::condition_variable maTasksChanged; + bool mbTerminate; + std::size_t const mnMaxWorkers; + std::size_t mnBusyWorkers; + std::vector< std::unique_ptr<ThreadTask> > maTasks; + std::vector< rtl::Reference< ThreadWorker > > maWorkers; +}; + +} // namespace comphelper + +#endif // INCLUDED_COMPHELPER_THREADPOOL_HXX + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |